HLR is an important device that stores subscriber data. As mobile subscribers grow rapidly and communication technologies develops progressively, the capacity of a single HLR often reaches to hundreds of thousands of records or even more. In case of long downtime due to power breakdown, fire disaster, earthquake or lightning strike, mobile services of relevant contract subscribers will be interrupted; therefore, it is urgent to implement remote backup for HLRs.
Presently, there are mainly two solutions: one is data backup only; the other is service backup based on data backup, i.e., if the active HLR fails, the backup HLR will take over the traffic to ensure uninterrupted traffic at its maximum. Owing that there are different manufacturers of HLRs and storage formats and processing modes of subscriber data in the HLRs, and that local data backup (i.e., periodical subscriber data backup on tape drive or disk) is implemented for the HLRs primarily, service backup is still in bud. Usually, remote backup solution is the incompatible 1+1 one, e.g., some developed commercial backup software from a third party is used or extensive MAP (mobile application part) signaling is implemented. The 1+1 backup solution may be an active/backup unidirectional one or a cycled one in mutual backup mode, and the extensive MAP (mobile application part) signaling is typically implemented to achieve 1+1 cycled backup. According to said method of 1+1 cycled backup, each HLR stores not only its own subscriber data but also subscriber data of the other HLR; the subscriber data is identified internally with “active/backup” identifier. Besides receiving and processing standard signaling or operation instructions to it according to normal workflow, each HLR also informs the corresponding backup HLR of varied subscriber data resulted from these signaling or operation instructions so as to enable the backup HLR to implement data synchronization. The extensive MAP signaling contains such operation instructions as modification, addition and deletion. The method has the following problems:
(1) High cost: Employing a backup system for each of the numerous HLRs in the network requires high cost, especially in case of low probability of HLR malfunction. Although the number of HLRs needs not to increase in 1+1 cycled backup mode, each HLR has to store the subscriber data of the other HLR, resulting in high upgrade cost.
(2) Complicated technology and long implementation cycle: The HLRs have to not only inform their counterparts of varied subscriber data in standard signaling mode but also receive and process subscriber data synchronization signaling from their counterparts, resulting in high workload in modification of software system.
(3) Difficult management: it is difficult to manage each HLR because it stores the subscriber data of the other HLR.
(4) Clear solution for compatibility is unavailable, in particular in backup of manufacturer-defined special service data.